# CLS Lean Specialist Exam Prep vs Echo Shelf.

The clearest difference is in-app purchases: Echo Shelf. at none against CLS Lean Specialist Exam Prep's 9. Echo Shelf. also leads on update cadence (every 3 weeks vs every 3 months) and iOS requirement (13.0 vs 15.1). On price, ads and device support there is nothing between them.

Both are free to download. CLS Lean Specialist Exam Prep sells 9 in-app purchases, starting at $8.99 per 7 days. Echo Shelf. asks for nothing beyond the download.

CLS Lean Specialist Exam Prep ships an update every 3 months, Echo Shelf. every 3 weeks. The most recent releases landed on November 4, 2026 and October 31, 2026 respectively.

## The numbers

| Metric | CLS Lean Specialist Exam Prep | Echo Shelf. |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (2 ratings)](https://appshunter.io/ios/app/cls-lean-specialist-exam-prep/id6743373867/reviews)** | — |
| Number of ratings | **2** | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 3 months | **Every 3 weeks** |
| Monetization | Free with in-app purchases | — |
| Size | 51 MB | 22 MB |
| Requires iOS | 15.1 | **13.0** |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Exam Prep OU](https://appshunter.io/developer/1689642184) | [My Vision Match LLC](https://appshunter.io/developer/1802686748) |

## What reviewers say

### CLS Lean Specialist Exam Prep

[App page](https://appshunter.io/ios/app/cls-lean-specialist-exam-prep/id6743373867)

Prepare for your Certified Lean Specialist (CLS) exam with this comprehensive study tool. It offers a vast question bank, detailed explanations, progress tracking, and simulated exams to help you master Lean principles and achieve certification.

**Highlights:** Extensive question bank, Detailed answer explanations, Progress tracking, Customizable study plans, Simulated exam mode, User-friendly interface

**Features:** macOS Compatibility

**In-app purchases (9)**

| Purchase | Price | Billing |
| --- | --- | --- |
| CLS Weekly Full Access | $8.99 | per 7 days |
| CLS Monthly Full Access | $24.99 | per month |
| CLS Monthly Full Access | $24.99 | per month |
| CLS Quarterly Full Access | $55.99 | per 3 months |
| CLS Quarterly Full Access | $55.99 | per 3 months |
| CLS Semiannual Full Access | $75.99 | per 6 months |
| CLS Semiannual Full Access | $75.99 | per 6 months |
| CLS Annual Full Access | $109.99 | per year |
| CLS Annual Full Access | $109.99 | per year |


### Echo Shelf.

[App page](https://appshunter.io/ios/app/echo-shelf/id6755823127)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is CLS Lean Specialist Exam Prep free?

CLS Lean Specialist Exam Prep is free to download, with in-app purchases available.

### Is Echo Shelf. free?

Echo Shelf. is free to download, with no in-app purchases.

### Do CLS Lean Specialist Exam Prep or Echo Shelf. have ads?

Neither CLS Lean Specialist Exam Prep nor Echo Shelf. shows ads.

### Which is updated more often, CLS Lean Specialist Exam Prep or Echo Shelf.?

CLS Lean Specialist Exam Prep ships an update every 3 months, and Echo Shelf. every 3 weeks. Most recently, CLS Lean Specialist Exam Prep was updated on November 4, 2026 and Echo Shelf. on October 31, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*